You may have a hardware issue (broken EEPROM) or the NVRAM partition is completely wiped. Try flashing a full stock ROM first.
To use the tool for IMEI repair, follow these general steps: How to Use Spreadtrum IMEI Tool v4
Spreadtrum IMEI Tool v4.1 (also known as the SPD WriteIMEI Tool
: Includes support for newer Unisoc Tiger chipsets like the T310, T606, T610, T612, and T616 , enabling RSA Auth bypass for more secure devices. How to Use Spreadtrum IMEI Tool v4.1
Modifying IMEI or device identifiers may be illegal in many jurisdictions and can void warranties or violate carrier policies. Use this tool only on devices you own or when authorized, and comply with local laws and carrier agreements.
: Supports a wide range of manufacturers such as Infinix, Tecno, iTel, Samsung, Realme, and Nokia .